Journal of Postharvest Technology 03 (04): 101-109, Oct’ 2015 www.jpht.info *Email: willis@agr.jkuat.ac.ke ISSN 2348-4330 The Effects of a Low Cost H ydro Cooling System on the Postharvest Quality Characteristics of Selected Tropical Fruits and Vegetables Joyce Chepngeno 1 , John Kinyuru 1 , Ngoni Nenguwo 2 , and Willis Owino 1 * 1 Department of Food Science and Technology, Jomo Kenyatta University of Agriculture and Technology, Kenya 2 The World Vegetable Center Eastern and Southern Africa, Tanzania Received : 04 July 2015 Revised : 12 Sep 2015 Accepted : 15 Sep 2015 Keywords Cooling time Hydrocooling Low temperature storage Postharvest Quality Abstract Quality of fresh produce getting to consumers is influenced by the postharvest handling practices. In developing countries, low cost hydrocooling system offers affordable means to curb postharvest loses of perishables. This study was undertaken to establish the effect of combining hydrocooling and low temperature storage on postharvest quality of perishables, specifically carrots, courgettes, tomatoes and African eggplants. Mature good quality produce were harvested and divided into four portions. Two portions were hydrocooled using chilled water (2±1 0 C) and change in temperature monitored. The other two were controls. Hydrocooled and control samples were stored at 10 0 C and 20- 25 0 C at 95%relative humidity. Respiration rates, weight loss, soluble solids and titratable acidity changes were assessed at 2 days interval for 9 days. The percentage weight loss on day 9 was 1.83 %, 13.91 %, 8.09 %, 6.25 % and titratable acidity was 0.24%, 0.019%, 0.13%, in samples hydrocooled and stored at 10 0 compared to 4.30%, 28.35%, 20.03%, 2.15%weight loss and 0.32%, 0.037%, 0.16%,titratable acidity in control for tomatoes, courgettes carrots and African eggplants, respectively. Respiration rates and soluble solids were higher in controls. Storage time had a significant effect (P≤0.05) on produce quality. INTRODUCTION Fruits and vegetables constitute an important subsector in horticultural industry in Kenya (KARI 2012). Besides their economic importance, they constitute a major part of human nutrition (Hounsome et al. 2008). However, due to their high perishability, limited postharvest technologies in most of the developing countries and inadequate cold storage, huge postharvest losses are incurred (Kitinoja et al. 2011). Temperature control plays an important role in preserving the quality of freshly harvested produce. Cool temperatures are essential in the preservation of flavour, texture, aroma volatiles, appearance and also in prolonging the shelf life and keeping quality of fresh produce (Teruel et al., 2004; Thorpe 2008). This is because low temperature slows down changes in physiological, chemical and physical composition of the produce (Khorshidi et al. 2010). Systems that facilitate fast cooling in fresh produce are important for rapid decrease in product temperature (Manganaris et al. 2007). Use of chilled water to cool the produce otherwise referred to as hydrocooling allows high heat transfer rates, resulting in shorter cooling time of produce. According to Manganaris et al., (2007), water removes heat about fifteen times faster than air. Although hydrocooling offers faster cooling, there are differences in time required to cool different products to the target temperature. This is due to differences in products geometry, size and the thermal properties (Teruel et al. 2004). Despite the well-known benefits of hydrocooling on postharvest life of perishables, the technique has not been fully utilized in developing countries due to the fact that conventional custom made hydrocooling systems are usually expensive, and out of reach for most subsistence farmers (FAO 2014; Kitinoja 2010). In order to reach out to a wide number of subsistence farmers it is imperative to assemble a hydrocooling system using locally available materials that are light in weight, flexible and which can easily be moved from one location to another as may be required. The present study was undertaken with the aim of establishing the time required to cool specific fruits jpht Research Article jpht Research Article